1. Field of the Invention
Embodiments of the invention relate to a liquid crystal display capable of improving response characteristic of liquid crystals.
2. Discussion of the Related Art
A range of application for liquid crystal displays has widened because of its excellent characteristics such as light weight, thin profile, and low power consumption. The liquid crystal displays have been used in personal computers such as notebook PCs, office automation equipments, audio/video equipments, interior/outdoor advertising display devices, and the like. A backlit liquid crystal display occupying most of the liquid crystal displays controls an electric field applied to a liquid crystal layer and modulates light coming from a backlight unit, thereby displaying an image.
The backlight unit is classified into a direct type backlight unit and an edge type backlight unit. In the direct type backlight unit, a plurality of light sources are disposed on a lower surface of a diffusion plate, and light from the light sources travels to a back surface of a liquid crystal display panel. On the other hand, the edge type backlight unit includes a plurality of light sources, that are disposed opposite each other on the sides of a light guide plate, and a plurality of optical sheets disposed between the liquid crystal display panel and the light guide plate. In the edge type backlight unit, the light guide plate converts line light or point light coming from the light sources into plane light, and the plane light travels to the back surface of the liquid crystal display panel via the optical sheets.
The liquid crystal displays serve as a display device capable of implementing three-dimensional (3D) image as well as a two-dimensional (2D) image by the development of various contents and circuit technique. The liquid crystal displays require an improvement of response characteristic of liquid crystals, so as to increase the display quality when implementing the 2D image or the 3D image.
Examples of a method for improving the response characteristic of the liquid crystals include (1) a method for changing a cell gap, (2) a method for changing a liquid crystal material to change the physical properties of the liquid crystals, and (3) a method for increasing a surface temperature of the liquid crystal display panel to improve Ton/Toff(turn on time/turn off time) characteristics of the liquid crystals. It is practically difficult to select the methods (1) and (2) because of the technical difficulty and the cost burden.
In the liquid crystal display using the direct type backlight unit, because the light sources of the direct type backlight unit are widely distributed under the liquid crystal display panel, the method (3) is effective in increasing the surface temperature of the liquid crystal display panel. However, it is difficult to achieve the thin profile of the liquid crystal display because of a necessary interval between the diffusion plate and the light sources, and the liquid crystal display using the direct type backlight unit is expensive. Hence, the liquid crystal display using the edge type backlight unit has been intensively developed in recent years.
As described above, because the light sources of the edge type backlight unit are disposed along the side of the light guide plate, it is difficult to transfer heat generated in the light sources to the surface of the liquid crystal display panel. Thus, the surface temperature of the liquid crystal display panel of the liquid crystal display using the edge type backlight unit is lower than that of the liquid crystal display using the direct type backlight unit. Therefore, the response characteristic of the liquid crystals of the liquid crystal display using the edge type backlight unit is worse than that of the liquid crystal display using the direct type backlight unit. When the response characteristic of the liquid crystals is degraded, a motion picture response time (MPRT) when the 2D image is implemented lengthens. Hence, a motion blur appears, and a 3D crosstalk, resulting in a doubled image of left and right eye images of the 3D image, appears.